Electric strain insulator



' Feb. 19, 1929.

- 1,702,315 R. M. REINHARDT .ELECTRIC STRAIN INSULATOR Filed Jan. 12, 1928 2 Sheets-Sheet l Feb. 19, T929. 1,702,315

R. M. REINHARDT I I ELECTRIC STRA IN INSULATOR Filed Jan. 12, 1928 2 Sheets-Sheet 2 l /5 7$: 75. 17. Fain Jar/7 W 404% W, W W

Patented Feb.'19, 1929.

UNITED STATES 1,702,315 PATENT OFFICE.

RICHARD MAX REINHARDT, OF BROMOLLA, SWEDEN, ASSIGNOR T AKTIEEOLAGET IFOVERKEN, OF BROMOLLA, SWEDEN, A CORPORATION OF SWEDEN.

ELECTRIC STRAIN INSULATOR.

Application filed January 12, 1928, Serial No. 246,323, and in Sweden July 27, 1927.

My present invention refers to an improvement in electric strain insulators and more specifically to an improvement in the means for securing the metallic strain pin to the non-conductive body of the insulator.

For securing the pin to the insulator body in strain insulators it has already been proposed to provide the pin with a washer consisting of separate parts or parts expansibly connected with each other, which parts after having been positioned within the interior cavity of the insulator are spread apart and form an abutment surface coacting with a corresprmding abutment surface or edge within the insulator cavity. These known arrangements involve, however, a number of substantial disadvantages the most serious of which are that the washer rests against the insulator in certain points only and that a tension exerted on the pin has caused a substantial. component of force acting in radial direction and tending to wedge the insulator body apart in the direction of the diameter. It has also been previously proposed to use a full ring or a sleeve as a securing means between the pin and the insulator body, such sleeve being of a comparatively soft material, such as for instance copper, and intended to be deformed after insertion so to enlarge its diameter for forming the necessary abutment surface. On account of the softness of the material a securing means of this kind will also have a wedg ing action on the insulator body, and besides it can provide a small abutment surface only, the size of which must be considered insv licient for a reliable construction.

My present invention intends to do away with all of these disadvantages and this re suit is obtained on account of the fact that the securing means proposed by me consists of a washer built up from two or more separate pa is having such a shape that they may be iiiseited into the insulator cavity after having been tilted into an inclining position to the of the same, and when inserted they may be tilted back again and placed crosswise to each other so as to form a compounded wa er, in which at least one of the parts is provided with shoulders or lugs straddling the adjacent part of the washer for preventing a relative rotation of the na s around the axis of the pin.

he surface proper is then on the one part of urnent- 5:; formed by the shoulders the washer and the ends of another part ex tending between said shoulders, so that the washer provides a substantially continuous abutment surface all around the circumference, and all parts or sections of said abutment surface being positioned substantially in the same plane perpendicular to the axis of the pin. By this means the stresses transferred from the pin to the insulator body during active service are distributed uniformly around the circumference of the latter, and no local wedging action occurs in any direction.

The securing washer is usually or normally built up from two parts only placed crosswise at an angle of 90 to each other, and this number of parts serves any useful purpose, but of course it is notimpossible to build up the washer from a greater number of parts, for instance three, placed at an angle of but it is not to be seen that the invention could be further improved thereby.

In the following the invention is to be described with reference to the accompanying drawings showing two different embodiments of the same, whereby each drawing shows one of them. In the drawings Fig. 1 shows the assembled insulator in axial section. Figs. 2 and 3 show the two parts forming the washer and Fig. 4 shows said parts when assembled, all of these figures being plan views. Figs. 5 and 6 are diagrams intended to explain the manner of insertion of the washer parts into the insulator cavity, as will be nearer explained below. Fig. 7 shows the second embodiment of the invention in the same manner as Fig. 1. Fig. 8 shows an elevation of the strain pin used in the second embodiment of invention. Fig. 9 shows the assembled washer according to this embodiment, and Figs. 10 and 11 show the washer parts, all of these three figures being plan views.

In the drawings the same references are used on similar parts in both of the embodiments and 1 represents the insulator body, the shape and size of which are to be chosen according to the voltage to be insulated. The said insulator body, as usual, is pro vided with an interior cavity 3, which by means of an axially positioned opening or channel 2 is open towards the bottom end of the insulator previous to the securing of the strain pin. The cavity/'3 is of a larger diameter than the opening 2 thus forming an offset which is to be utilized as abutment surface for the securin washer. This abutment surface, for the purpose of centering the pin, is of a conical shape, but the apex angle of the truncated cone thus formed is to be chosen so great as possible.

On the exterior of the insulator body 1 is afilxed a cupshaped member 4 provided with a recess 5 for insertion of the outer head of the strain pin secured to another insulator body so as to make it possible to couple more separate insulators together into a chain of suliicient length, as usual in the art. In both of the embodiments shown in the drawings the strain pin 6 is provided with an outer head 7 for this purpose, but whether such head is at hand or not is of no influence on the invention and-this head forms no part of the same, as will be understood from the following.

In the embodiment according to l6 the strain pin 1 at its inner end, which is intended for insertion within the cavity 3, is provided with a head 8, suitably of a convex shape shown, and at the under side of this head the pin is provided with an oblong and preferably oval oiilset portion or key 9, which has a width preferably of the same dimension as the diameter of the pin and a length somewhat smaller than the diameter of the head 8. This key serves the purpose of preventing the rotation of the securing washer around the axis of the pin, and it is intended to be inserted into a corresponding hole in one of the washer parts, as will be nearer de scribed below. The presence or" this lzey not positively necessary and, if it is at hand, in may be given several other shapes than the one shown and described.

The securing w sher is built up from two arts, of which the part 10 positioned nearest to the head 8 is referred to as the inner one, the second part 11 being termed the outer one. As to the shape in plan view, i. e. looking in. the direct-ion of length of the pin, both of the washer parts are confined by two opposite and arc-shaped edges and two intermediate Sl'l'ilfglll-lllltl edges bstantially parallelto each other. If the length of are in both parts is 1 3, as shown in the drawing; both of them. when placed crosswise ad jacent to each other, will form a substan tially minplete circle and thereby also a continuous washer part 10 5) pro- The inne isher vidcd with a central hole corresponding in shape to the shape of the key 9, but the oblong shape of this hole serves also another purpose, i. e. for making: it possible to insert the washer into the cavity 3 in the manner nearer described below. For this latter purpose the outer washer part 11 2) also provided with a similar hole 13. 7

At least one of the washer parts, in 'h l. stance the-inner part 10, at the side facing the outer part 11 is provided with lugs 14 extend ing towards the latter, said lugs being of a segmental shape and of a height or extension corresponding to the thickness of the central section of the outer washer part 11. The outer washer part 11 may preferably also be provided with similar lugs 15 located at the arc-shaped edges. These latter lugs are not essential for the construction but may be useful for inci -asing the rigidity of the securing washer after assemblance, and they are intended to straddle the straight-lined edges of the inner washer part.

On account of the hei zht or extension of the lugs 14 on the inner washer part 10 described above they will be positioned substantially in thesame plane the ends of the outer washer part extending between them and as well said ends said lugs are given a coinciding conical sh ape, corresponding to the shape of the abutment surface within the insulator body, so as toform a substantially continuous abutment surface of the pin which surface all around the circumference positioned subs "llll tliLlly in the same plane perpendicular to the axis of said pin.

In Figs. -4 the washer parts re shown from the outerend of the pin, and if the inner part- 10 (Fig. be turned an angle of 90 from the position shown in the drawin and the outer part 11 (Fig; 52) former, without alteration of its position as shown, the assembly shown in Fig. 4 will be obtained, the two concentric circles in said figure indicating the abutment surface formed by the assembled washer parts.

The strai 'ht-lined edges of the part 10 at O 2; placed on the the side of the same facing the part 11 are provided with notches 18, and the arc-shaped edges of the part 11 at the side facing e part 10 are provided with similar notches corresponding in position to the aforesaid notches i6 and extending into the central hole I'Vhen assembl ng: the parts as shown in Fig.

' lthe notches l6 and 17 will he brought into at 18 by means of secured to the insuregister and form holes or channe for the easily fusible metal, which the pin is usually lator body, so that said metal may penetrate the washer and flow into the cavity 3 atthe inner side of the same, even if the washer should be kept in contact with the abutment surface of the insulator body.

In order to support the washer i in the insulator bod when pour in the molten sealing metal that the dififereut parts of the washer are not l'elati vely to each other or to the str preferable to arrano'e a sleeve 15) part of the pin. positioneu with tor body, said sleeve being l 4)., 1 rails mile-- washer part ll, the outer end oi. 5.1

ing against lugs 20 arranged on the pin. This sleeve is intended to be atlixed by the sealing metal at the same time as the securing washer and the strain pin, whcreattcr the sealing metal will laterally support the sleeve, the lugs 20 supporting the same in axial direction, so that it will be positively a'ilixcd to the structure a whole.

The manner oi? insertion of the pin and the securing washer will be understood trom Figs. and (i. The strain pin is at first to be inserted so that: the head 8 takes the position shown in Fig. 5 and the pin itself is kept in a somewhat inclined position within the channel 2. Thereafter the inner washer part 10 is tilted into an. inclined position in relation to the pin, as shown, so that its projection on a plane perpendicular to the axis of the channel 2 is smaller than the cross sectional area of said channel, this tilted position being possible on account of. the oblong shape of the hole 12. Then the inner washer part along the pin may be pushed into the cavity 3, wherein it is tilted back again to a position perpendicular to the pin and advanced towards the head 8 so that the key 9 enters the hole 12, as shown in Fig. 6. The outer washer part 11 is thereafter tilted in the same manner in relation to the pin, pushed home and tilted back again whereatter it is turned in relation to the inner washer part, so that the lugs on the latter straddle the central section oi the for mer and the lugs 15 eventually at hand on the outer washer part extend upwardly between the lugs 14 on the inner one. At last the parts of the split sleeve 19 nay be positioned around the pin as described and the whole pin structure is thereafter cast tight by pouring in molten sealing metal through the channel 2 in the manner described above whereby such metal by means of the channels 18 flows into the cavity 3 at the inner side of the head 8, even it the compounded washer should be in contact with the corresponding abutment surface of the insulator body.

It is to be understood that it is not necessary at all times to use the split sleeve 19, since the insulator body is turned upside down when pouring in the sealing metal and then the weight of the same will usually prevent the disp moment of the washer parts waethcr the split sleeve is at hand or not.

in the nuiditication according to Figs. T ll the same references are used on corr sponding parts and the ditl'crence betweei'i the two embodiments shown is mainly to be found in the tact that the strain pin according to the last en'ibodiment has a threaded end and is adapted to be screwed into a threaded hole within at least one of the washer parts, i. e. the inner one, and thereafter to be locked in a suitable manner.

The washer 10, 11 also in this case is carried out in the same manner described above, but. instead of the oval holes 12 and 1.3 crossing each other, in the assembled washer the washer parts in this instance are provided with cylindrical holes for penetration by the strain pin. The end of the pin 6 is threaded at 6' and the hole 21 in the inner washer part 10 is provided with threads, the corresponding hole 22 in the outer washer part 11 being smooth. Somewhat below the threaded end 6 the bolt 6 is provided with an abutment of suitable kind, for instance a collar or a pair of lugs 23 as shown in the drawing, and when the screw is screwed home in the inner washer part 10 said lugs will cause the outer 'asher part 11 to be pressed against the former, so that an axial dis ilacen'ient of the washer parts will thereafter be prevented. A relative rotation of the washer parts will also be prevented on account of the lugs lei, and eventually the lugs 15, in the same manner as described above, whereatter the only movement possible is a simultaneous turning of both oi the washerparts around the pin. This move ment will, however, also be prevented it the threaded end of the pin in one manner or another be locked in relation to the pin, and for such purpose both of the washer parts 10, 11 may be provided with slots 24, 25 which after the assembly come into register with each other and with a corresponding slot 2 in the screw, so that apin or key 26 Fig. 7) may be driven through said registering slots.

Also in this latter embodiment the washer parts may be inserted into the insulator cavity in the same manner as described above, although they are completely free and not sur rounding the strain pin at the insertion. After the insertion of the washer parts as described and after the crosswise positioning of the same in relation to each other the threaded end 6 ot the pin is freely pushed through the hole in the outer washer part 11 and screwed into the threaded hole in the in nor washer part 10. Thereafter the pin is locked to the washer as described or in any other suitable way, as commonly used in the art, and the securing of the pin is completed by pouring in the sealing metal in the same manner as described above.

Also in this instance the washer parts 10, 11 may be provided with holes or channels which come into register after the assembly of the same and serve the purpose of permitting the sealing metal to flow freely into the cavity 3 at the inner side of the washer.

The hole 22 in the outer washer part 11 may of course also be provided with interior threads for the threaded end of the pin, but such means are entirely superfluous and would cause a ditiiculty in obtaining a tight contact between the washer parts. Any

means corresponding to the split sleeve 19 need not he used in this modification.

What I claim and desire to secure by Letters Patent is 1.. An improvemei'u' in electric strain insulators comprising an insulator body provided with an interior cavity open to the bottom end of said body and forming an abutment surface, a strain pin, one end of which is adapted for insertion in the said cavity, securing washer positioned at the inner end of said strain pin within the insulator cavity, such washer consisting of at least two separate and oblong parts placed crosswise to each other and at least one of them at the side facing an adjacent washer part being provided with lugs straddling the lastmentioned washer part in such a manner that said lugs are positioned in substantially the same plane perpendicular to the strain pin as the ends of said adjacent washer part, said lugs and the ends of the adj a'cent washer part being shaped into the form of a substantially continuous abutment surface extending around the whole circumference of the securing washer.

2. An improvement in electric strain insulators comprising an insulator body pro vided with an interior avity open to the bottom end of said body and forming an abutmentsurlace, a strain pin, one end of which is adapted for ii sertion in the said cavity, a securing washer positioned at the inner end of said strain pin within the insulator cavity, such washer being builtup by two separate parts oblon in shape ant, placed crosswise to each other, the inner one of said washe" parts at the side facing the enter one being provided with lugs straddling the lastmern tion-ed washer part in'such a way that said lugs are positioned substantially in the same plane perpendicular to the strain pin the ends of the outer washer part, said lugs and ends being shaped into the form of a substantially continuous abutment su cc around the whole circumference of the securing washer.

3. An improvement in electric strain in sulators comprising an insulator body provided with an interior cavity open to the bottom end of said body and forming aoutment surface, a strain pin, one end wh'c is ad pted to'l e inserted in the said cav' a securing washer posfl one; at the i end of said strain pin within the insul cavity, such washer oei 51' built up by two separate parts oblong: in shape d placed crosswise to each other, both 0*"? said wash r parts at the sides facing each other being provided with intermcshing lugs positioned substantially in the same plane perpendicular to the strain pin and shaped i to the term of a suhst-znltially conlinuon abutine surface around L-AG whole circumference of t re scour lllfif washe 4. An improvement in electric strain insulators comprising insulator body,

interior cavity therein open to the bottom end of said body, an abutment surface formed within said cavi a strain pin, one end of which is adapted for insertion the insula tor cavity, a secin'ing washer positioned at the inner end of said pin and built up from least two oblong parts placed crosswise to each other, means at the ends of said washer parts for forming a substantially continuous abutment surface around the whole circumference of the washer, means for pr venting an axial displacement of the Washer parts in relation to the strain pin due to stresses arising in active service, means for preventing a rotation of the washer parts in relation to each other around the axis of the pin and means for preventing the rotation of at least one of the washer parts in relation to the pin around the axis of the same.

5. An improvement in electric strain insulators comprising an insulator body, an

interior cavity therein open to the bottom end of said body, an abutment surface formed within said cavity, a strain pin, one end of which is adapted for insertion in the insulator cavity, a securing washer positioned at the inner end of said pin and built up from two oblong washer parts placed crosswise to each other, lugs at the ends of the inner washer part straddling the outer one, such lugs and the ends of the outer washer part being shaped into a substantially continuous abutment surtace around the whole circumference of the securing washer, means for preventing an axial displacement of the washer parts in elation to the pin due to stresses arising din a service, means for preventing a rotation of the washer parts in relation to each other around the axis of the pin and means for preventing the rotation of at least one of the vashe parts, preferably the inner one, in relation to the pin around the axis of the same. r An improvement in electric strain inanprisii'ig an insulator body, an in- ,vity therein open to the bottom end "un said cavity, a strain pin, one end of which is adapted for insertion in the insulator cavity, hea d on'tlie inner end said pin, an inner washer member oblong in shape and provided with an oblong hole for i on h the pin, an outer washer memie former, lugs arranged one of th washer menuthe aujacent washer prey on the strain pin and into the oblong hole her members and thereby i oi the same around the axis or the pin and means at the ends of the was r parts forininq' a. substantially c at. nuous abutment suritace around the whole circumfe of the compounded washer,

3'". An improvement in electric strain insulators eoinpris-ng an insulator body, an interior cavity the iopen to bottom end of said body, an abutment surface formed within said cavity, a strain pin, one end of which is adapted for insertion in the insulator cavity, a head on the inner end of said pin, an inner washer member oblong in shape and provided with an oblong hole for penetration by the pin, an outer washer member carried out in the same manner and placed crosswise to the former, means at the outer ends of said washer parts for forming a substantially eon tinuous abutment surface around the whole circmnli'erence oi the compounded washer, means for preventing a rotation of the washer parts relative to each other around the axis oi the pin, means for preventing a rotation of at least one ot the washer members in relation to the pin. around the axis of the same, abutuicnts positioned on the pin at a distance from the head of the same and a longitudinally split sleeve member positioned between said abutments and the inner washer member.

8. An improvement in electric strain insulators COHlpl'lSlng an insulator body, an interiorcavity therein open to the bottom end of said body, an abutment surface formed within said cavity, a strain pin, one end of which is adapted for insertion in the insulator cavity, a securing washer positioned at the inner end on said pin and built up from at least two oblong parts placed crosswise to each other, means at the ends of said washer parts for forming a substantially continuous abutment surface around the whole circumference the compounded washer, means preventing axial displacement of the securing washer in relation to the strain pin due stresses arising in active service, means for preventing a rotation between the Washer parts in relation to each other around the axis of the pin, means for preventing the rotation of at least one oi said parts in relation to the pin around the axis of the same and channel means arranged through the compounded washer structure for connecting the space at the outside of the same with the insulator cavity at the inside of said structure.

In testimony whereof have signed my name to this specification.

RICHARD MAX REINHARDT. 

